Field of the Invention
The present invention relates to a nickel composite hydroxide and a production process therefor, a positive electrode active material and a production process therefor, and a non-aqueous electrolyte secondary battery. More particularly, the invention relates to a nickel composite hydroxide for a precursor for a lithium-nickel composite oxide which is used as a positive electrode active material in a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, and a production process therefor, a positive electrode active material and a production process using a nickel composite hydroxide for a precursor, and a non-aqueous electrolyte secondary battery that uses the positive electrode active material. It is to be noted that the present application claims priority based on the Japanese Patent Application No. 2014-133402 filed on Jun. 27, 2014 in Japan.
Description of Related Art
In recent years, along with the popularization of mobile devices such as cellular phones and lap-top personal computers, the development of small and light secondary batteries with a high energy density has been desired strongly. Such secondary batteries include, for example, lithium ion secondary batteries that use lithium, lithium alloys, metal oxides, carbon, and the like as negative electrodes, which have been actively researched and developed.
Lithium ion secondary batteries that use lithium metal composite oxides, in particular, lithium-cobalt composite oxides for positive electrode active materials achieve high voltages on the order of 4 V, which have been thus expected as batteries with a high energy density, and progressively put into practical use. Large numbers of batteries that use lithium-cobalt composite oxides have been ever developed in order to achieve excellent initial capacity characteristics and cycle characteristics, and various results have been already achieved.
Positive electrode active materials which have been ever mainly proposed can include lithium-cobalt composite oxides (LiCoO2) which are relatively easily synthesized, lithium-nickel composite oxides (LiNiO2) and lithium-nickel-cobalt-manganese composite oxides (LiNi1/3Co1/3Mn1/3O2) which use more inexpensive nickel than cobalt, and lithium-manganese composite oxides (LiMn2O4) which use manganese, and spherical or substantially spherical particles easily synthesized are used mainly.
Main characteristics of batteries that use the positive electrode active materials include a capacity and a power density, and a high power density is required for, in particular, hybrid in-car batteries for which there has been increasing demand in recent years.
Methods for improving the power density of a battery include the reduction in the thickness of electrode films for use in secondary batteries, and for example, in hybrid in-car batteries, films on the order of 50 μm in thickness are used. The reason that the thickness of electrode films can be reduced in hybrid in-car batteries is because the movement distance of lithium ions is reduced. As just described, there is a possibility that the positive electrode active materials for use in thin electrode films will break through the electrode films, the positive electrode active materials are thus limited to small-size particles that are uniform in particle size, and in the case of electrode films for hybrid in-car batteries, particles on the order of 5 μm are used.
However, when such small-size particles are used for electrode films, the volume energy density which is an important characteristic along with the power density is disadvantageously decreased because of the low electrode densities.
Patent Document 1: JP 2012-84502 A